What is the first‑line antibiotic and dosing for acute otitis media in a 10‑month‑old infant (~9 kg), and what alternatives are recommended if the child has recent β‑lactam exposure, conjunctivitis, or a penicillin allergy?

First-Line Antibiotic for Acute Otitis Media in a 10-Month-Old

For a 10-month-old infant with acute otitis media, prescribe high-dose amoxicillin at 80-90 mg/kg/day divided into 2 doses for 10 days as first-line therapy. 1, 2

Standard First-Line Treatment

• Amoxicillin 80-90 mg/kg/day in 2 divided doses is the recommended first-line antibiotic for most children with AOM, including this 10-month-old infant 1, 2, 3
• For a 9 kg infant, this translates to approximately 360-405 mg twice daily (720-810 mg total daily dose) 2
• Treatment duration must be 10 days for all children under 2 years of age, regardless of symptom severity 2, 3
• High-dose amoxicillin achieves middle ear fluid concentrations adequate to overcome penicillin-resistant Streptococcus pneumoniae, the most common pathogen 2, 4

When to Use Amoxicillin-Clavulanate Instead

Switch to amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component + 6.4 mg/kg/day clavulanate in 2 divided doses) if: 1, 2, 3

• The child received amoxicillin within the past 30 days 1, 2
• Concurrent purulent conjunctivitis is present (strongly suggests Haemophilus influenzae infection, which produces β-lactamase) 1, 5
• History of recurrent AOM unresponsive to amoxicillin 1
• The child attends daycare or lives in an area with high prevalence of β-lactamase-producing organisms 2

Important dosing note: Use twice-daily dosing of amoxicillin-clavulanate rather than three-times-daily, as it causes significantly less diarrhea while maintaining equivalent efficacy 2

Penicillin Allergy Alternatives

For non-severe (non-type I) penicillin allergy: 1, 2, 3

• Cefdinir 14 mg/kg/day in 1-2 doses (preferred for once-daily convenience) 1, 4, 6
• Cefuroxime 30 mg/kg/day in 2 divided doses 1
• Cefpodoxime 10 mg/kg/day in 2 divided doses 1

For severe type I hypersensitivity (IgE-mediated) reactions: 2, 3

• Azithromycin (though less effective than amoxicillin for AOM) 3, 6
• Avoid trimethoprim-sulfamethoxazole due to substantial pneumococcal resistance 2, 5, 7

Cross-reactivity between penicillins and second/third-generation cephalosporins is lower than historically reported, making cephalosporins generally safe for non-severe penicillin allergies 1

Critical Management Components

Pain management is mandatory and must be addressed immediately: 2, 3

• Acetaminophen or ibuprofen at age-appropriate doses 2, 3
• Continue analgesics throughout the acute phase, as antibiotics provide no symptomatic relief in the first 24 hours 2, 3
• Even after 3-7 days of antibiotics, 30% of children under 2 years still have persistent pain or fever 2, 3

Reassessment at 48-72 hours is required if: 1, 2, 3

• Symptoms worsen at any time 1
• Symptoms fail to improve within 48-72 hours 1, 2
• If treatment fails on amoxicillin, switch to amoxicillin-clavulanate 2, 3
• If treatment fails on amoxicillin-clavulanate, use ceftriaxone 50 mg/kg IM daily for 1-3 days (3-day course superior to 1-day) 1, 2

Common Pitfalls to Avoid

• Do not use observation without antibiotics in this 10-month-old – all children under 6 months require immediate antibiotics, and children 6-23 months require antibiotics if bilateral AOM or severe symptoms are present 2, 3
• Do not prescribe a 5-7 day course – children under 2 years require the full 10-day duration 2, 3
• Do not use standard-dose amoxicillin (40-45 mg/kg/day) – high-dose is essential for resistant organisms 1, 2
• Do not treat persistent middle ear effusion after symptom resolution – 60-70% of children have effusion at 2 weeks post-treatment, which requires monitoring but not additional antibiotics unless it persists beyond 3 months with hearing loss 2, 3